The present invention relates to Orthogonal Frequency Division Multiplexing OFDM based optical communications, and, more particularly, to an energy efficient OFDM transceiver.
As the telecom industry is facing an exponential increase of network capacity, energy efficiency has become a growing concern. Statistical results show that periodic variations of the traffic volume in telecom networks are significant. Attention is directed to FIG. 1, depicting the daily traffic volume at an Amsterdam internet exchange. An energy-efficient network should be able to follow these variations. However, especially in the optical core network, all pieces of equipments required to carry the peak-traffic are powered on permanently, regardless of the capacity actually being transported.
Several Prior attempts to solve the problem from different aspects have failed to provide a satisfactory energy efficient technique. One attempt employed selectively turning off network elements. This solution turns off the optical link (and the corresponding line card) when traffic is low, and uses traffic re-routing to provide network connectivity. The drawback is that when the optical link is turned off, it will take long time to power it on and have it stabilized. This becomes critical issue in case of emergency, in which huge volume of traffic might happen when some links are powered off in low traffic period.
Another attempt was directed to an energy efficient network design. This attempt tried to solve the problem from the network architecture side, to minimize the power consumption of routers and optical components (e.g., EDFAs, transponders). The network elements still cannot track network. In a yet further attempt, energy efficient IP packet forwarding was employed to solve the problem from an internet protocol IP layer, for example, by using different packet size, or by using pipelined switching, Lastly, another attempt employs Green routing. This solution uses energy consumption of network elements as the optimization objective, and the energy-aware routing scheme considers.
The first solution considers from physical elements, but because of the aforementioned drawback, it is not likely to be taken by service providers. The remaining above solutions are from network architecture or higher-layer processing, which could only optimize the power consumption, not able to achieve the lowest possible level.
Accordingly, there is a need for an efficient OFDM transceiver that overcomes the shortcomings of prior techniques